Pneumatic tube systems (PTS) are a well-known means for the automated transport of materials between, for example, an origination location and any one of a plurality of destination locations. A typical PTS includes a number of pneumatic tubes interconnected in a network to transport carriers between user stations. Various air sources/blowers and transfer units provide the force and path control means, respectively, for moving the carriers through and from tube-to-tube within the system. Generally, transfer units move or divert pneumatic carries from a first pneumatic tube to a second pneumatic tube in order to route the pneumatic carrier between locations, such as stations, in the PTS.
The pneumatic tubes that form a network of pathways may be arranged in any manner. Many systems include a number of individual stations that are interconnected to the network by a single pneumatic tube. The single pneumatic tube transfers carriers to and from the station under pressure and vacuum and is connected to a transfer device. Such transfer devices allow for redirecting pneumatic carriers to one or more additional pneumatic tubes. In this regard, carries may be routed between different stations. It will be appreciated that the number of stations and distances between stations in the network may be quite large. For instance, many large facilities (e.g., hospitals) incorporate pneumatic tube systems having dozens or even hundreds of user stations where the distance between the most distally located pair of stations may exceed several hundred yards or even several miles.
Large PTSs often require a complex network of interconnected tubes. Further, to provide functionality to separate portions of such large systems, most such systems are divided into multiple zones. Typically, each zone includes a set of stations that receive pneumatic pressure and/or vacuum from a common air source. For instance, a transfer device that receives pressure and/or vacuum from the common air source may connect to each station of such a zone. This transfer device permits carriers received from pneumatic tubes connected to each station to be transferred to another pneumatic tube associated with one of the other stations (e.g., intra-zone transfer) and/or transferred to a different zone (e.g., inter-zone transfer).
During a transaction, a pneumatic carrier is placed in a first station and a destination (e.g., second station) is provided for the carrier. A pneumatic tube connected to the station is then fluidly connected to the air source by aligning various transfer devices to connect pneumatic tubes between the air source and the station. At this time, the air source typically applies a vacuum to the pneumatic tube, which moves the carrier out of the station and into the pneumatic tube system. The carrier proceeds under vacuum until it reaches a turn-around location where the carrier is stopped. Various transfer devices are then realigned to connect pneumatic tubes, which provide a pneumatic path toward the ultimate destination of the pneumatic carrier. At this time, the air source typically provides positive air pressure to propel the pneumatic carrier from the turn-around location towards its ultimate destination through the realigned transfer devices and connected pneumatic tubes. If the ultimate destination is in the current zone (i.e., an intra-zone transfer) the carrier proceeds to its ultimate destination. If the ultimate destination is in a different zone (i.e., inter-zone transfer) the carrier proceeds to an adjacent zone for further processing. During each air source cycle (e.g., application of pressure or vacuum) one carrier is moved from one location to a second location. Thus, it requires two air source cycles to move one carrier from an originating station into the PTS and to initiate movement of the carrier towards its ultimate destination.